Uranium is the heaviest of the naturally occurring elements. It can be found in row seven of the periodic table and is a member of the actinide group. Uranium atoms have 92 electrons and 92 protons with six valence electrons. There are 146 neutrons in the most abundant isotope.

Characteristics and Properties

Under standard conditions uranium is a hard silvery metal. It is malleable (meaning it can be pounded into a thin sheet) and ductile (meaning it can be stretched into a long wire). It is very dense and heavy.

Pure uranium is radioactive. It will react with most nonmetallic elements to make compounds. When it comes into contact with air, a thin, black layer of uranium oxide will form on its surface.

Uranium-235 is the only naturally occurring isotope that is fissile. Fissile means that it can sustain a chain reaction of nuclear fission. This characteristic is important in nuclear reactors and nuclear explosives.

Where is it found on Earth?

Uranium is about the 50th most abundant element in the Earth's crust. It can be found in very small traces in most rocks and in the ocean water. In the Earth's crust it is found in minerals such as uraninite, carnotite, torbernite, and coffinite.

How is uranium used today?

The main use for uranium today is for fuel in nuclear power plants. Nuclear power plants generate power by causing a controlled fission chain reaction using uranium. This produces a huge amount of energy from a small amount of uranium. One kilogram of uranium can produce as much energy as 1500 tons of coal.

Uranium is also used by the military for special ammunition. Depleted uranium (DU) is used in bullets and larger projectiles to make them hard and dense enough to punch through armored targets. It is also used to improve the metal armor used on tanks and other armored vehicles.

The Atomic Bomb

Uranium was used to create the first atomic bomb used in World War II. This bomb was called "Little Boy" and it was dropped on Hiroshima, Japan. Today nuclear bombs use other materials such as plutonium.

How was it discovered?

Uranium was discovered by German chemist Martin H. Klaproth in 1789. He discovered the element while experimenting with the mineral pitchblende. Uranium was not fully isolated until 1841 by French chemist Eugene Peligot.

Where did uranium get its name?

It was named by Martin Klaproth after the newly discovered planet Uranus.

Isotopes

Uranium has three naturally occurring isotopes. Uranium-238 is the most stable and makes up over 99% of the naturally occurring uranium.

Interesting Facts about Uranium

Yellowcake is an intermediate step in refining pure uranium. It is a yellow powder made up of mostly uranium oxide.